Health Plans work on annual enrollments and life events.
There is an annual enrollment period. Health care companies set rates for the next year. You are allowed a window. As this is the first year for obamacare, you have till the end of march, as you can’t go 3 mos. without hitting the penalty.
Health care companies have the concept of a “Life Event”. I lost my job. I got a new job. I had a kid.
These cause a new window to enroll based on the event. Obamacare follows this pattern.